Seed Germination

Seed Germination Name

This exercise is going to be your focus for the laboratory report this semester. So this project will involve setting up an experiment with a counted number of seeds, observing the number of seeds which sprout in the experiment, statistically analyzing the class results, and reporting the results in the format of a standard laboratory report. In addition to the materials provided in class, you will need to use the departmental style manual (Pechenik, J. A. 2004. A short guide to writing about biology. 5th ed. Addison Wesley-Longman Press.) for writing your laboratory report.

The effect of light on seed germination

A. Observation. Seeds of some species germinate in the light but do not do so well in the dark. The pigment phytochrome has two forms, Pr and Pfr, which absorb red and far-red light, respectively. Perhaps this pigment helps seeds detect the light.

B. Question. Do species requiring light to germinate use the phytochrome pigment to determine if they are in the light or darkness?

C. Hypothesis. Light-sensitive seeds do use the phytochrome pigment.

D. Prediction. If the hypothesis is true, then lettuce seeds placed in red light will germinate much better than seeds placed in darkness or far-red light. Moreover, seeds in far-red light should be particularly inhibited.

E. Experiment. Obtain four Petri Dishes from the supply and put one disc of filter paper in the bottom of each dish. Label the dish covers (and bottoms!) with the marking pen. The labels should include: White Light Red Light Far-red light Dark Control

Put 5 mL of distilled water in each dish, and obtain a square of aluminum foil so that you are ready to wrap the “dark” dish immediately. BE READY!

With your partner, carefully count out three groups of 50 lettuce (Lactuca sativa ‘Tango’) seeds. Of course the counts must be accurate, but WORK QUICKLY! Place one group of 50 seeds into each dish on top of the moist paper.

IMMEDIATELY wrap the "dark"...